X-ray radiation time recorder and controller



Nov. 7, 1950 w. B. POND A 2,528,545

X-RAY RADIATION TIME RECORDER AND CONTROLLER Filed May 19, 1946 3 Sheets-Sheet 1 jiiq.1.

KLI n WLL/AM B Po/vo,

INVENTOR.

ATTaQ/vEY.

Nov. 7, 1950 w. B. POND X-RAY RADIATION TIME RECORDER AND CONTROLLER :5 Sheets-Sheet 2 Filed May 19, 1946 km WW a m B m m m m BY Q? Arrae/vsx Nov. 7, 1950 w. B. POND 2,528,545

X-RAY RADIATION TIME RECORDER AND CONTROLLER Filed May 19, 1946 3 Sheets-Sheet 3 WILL/AM 3 Fave INVENTOR.

v BY 4 Patented Nov. 7,

UNITED STATES omcs X-RAY RADIATION TIME nnoosonit Am; CONTROLLER William B. Pond, Arcadia, Calif assig'iiot to Transrese'arch of California, Pasadena, Calif.,

a partnership Application March 19, 194-6,- serial Nb. 6555444 12 Claims. (01150-95) 1 This invention relates generally to'a recording and control apparatus and more specifically to a radiation exposure time recording and control apparatus which might, for example, be used to record and control the exposure time to X "rays of a physician, operator, patient, or-other person who might be'exposed. While the apparatus is primarily intended for medical wait-might also be used industrially, or in many other applications. v

There are numerous automatic X-ray timers well known in the prior art. "However, such timers are generally of the type which automatically turns oi the X-ray generator after a apparatus first positions the patient or other object to be exposed to X-rays then the operator measures the distance through the object to be traversed by the X-rays in a direction parallel to the passage of the X-rays through the person or object, then takes into account the densit of the medium to be traversed by the X-ray and keeping the above points in mind, the operator malges appropriate settings of the kilovolts acrossthe X-ray generator tube and the milliamperes through the filament of the X-ray generator tube. Since both the adjustment of the kilovolts across the tube and the milliamperes through the filament afiect the quantity and intensity of the X- rays generated, the optimum exposure time'for a photographic medium such as plate, film, etc., which is placed On the opposite side of the object or person to be photographed, will be a function of said kilovolt adjustment, said milliampere adjustment, the density and thickness of the person or object to be traversed by the X-rays and the distance between the X-ray generator and the photographic medium. Keeping the above points in mind, the physician or operator determines the correct exposure time for the photographic medium and sets the automatic X-ray timer so as to shut off the X-ray generator at the end of such exposure time. Such prior art, automatic X-ray timers function admirabl where the X-ray generator is adapted to expose a photo graphic medium.

l-Iowever, such prior art, automatic X-ray e'x-' "pssure time -apparatus are "almost completely useless in fluoroscbpy. In fluoroscopy the physician or operator positions thepatientorbbject tobeexamin'ed between an X-ray generator and a fluorescent screen which generally comprises any suitable transparent material coated with any suitable fluorescent material such as'barium platinocyanide or zinc sulfide. The patient 'br object to'be examined 'casts shadows "on said fiuo'rescen't's'creen which maybe visually observed by the physician o r ope rator of the X-ray apparatus.

' In fluoroscopy it is often desirable to examine the object'for a period "of time, shut off the X- ray generator, reposition the object to be examined,'turn'on the X-ray generatoragain, andexamine the object'or patient a second time. This intermittent operation may be repeated many times an'd'the elapsed time of 'ea'ch'expo'sure isde- 'termined the physician or the operator of the X-ray gen'era'to'r, generally 'by means of a. foot switch which is depressed by the physician or; as-

erator when it'i's desired to examinethe patient and which is released when it is desired to stop the examination, either momentarily or otherwise. Since over-exposure to X-rays will serious- 13/ harm a being, it is essential that some means of recording and integrating the total elapsed time of 'allof the various exposures-be provided which will also automaticall shut "on the X-ray'gehera'tor after such integral or total time of such exposures excee d's a predetermined,

"safe value which "is 'Well within'the same range There has been need for such an exposure time recording and control device for recording and controlling exposure time of gamma radiation widely used'in'industrialapplications. There has also been need of such anexposure time recording and dependence for recording and controlling "exposure time to ultra-violet radiation, to infra-red radiation, and, in fact, many radiation, an e ces'sdr which may be harmful 'to human beings. Th'efe has also been need for a simple, fool-proof, integrating and recording "apparatus adapted to integrate and record electril Surges: il fhe be e d e impl cheap, fool-proof apparatus which will integrate and record the length of time during which any 'condition d'eparts from a predetermined norm.

, It would be of greae e'v'anage to have an X-ray exposure time recording apparatus adapted for medical use which would-provide an individualrecord of the total em 'sea exposure time of each individualpatient.

With the above points in mind, it is an object of this invention to provide a radiation exposure time recording apparatus adapted to integrate and record the total elapsed time during which a radiation generator is operating.

It is a further object of this invention to provide a radiation exposure time control apparatus adapted to automatically shut off a radiation generator after the total operation time of said radiation generator has reached a predetermined value.

It is a further object of the present invention to provide a radiation exposure time control apparatus adapted to flash on a warning lightafter a total period of operation time of said radiation generator has reached a predetermined value.

It is a further object of the present invention to provide a recording apparatus adapted to integrate and record the total elapsed time of elec-' trical overloads or surges, as for example, in a .power line, etc. i It is a further object of the present invention to provide a recording apparatus adapted to integrate and record the total elapsed time during which a physical condition has departed from a predetermined norm.

It is a further object of this invention to provide an X-ray exposure time recording and control apparatus primarily adapted for use in fluoroscopy .for integrating and recording the total elapsed exposure time to X-rays and for auto- .matically shutting off the X-ray generator after a predetermined, total time.

It is a further object of the present invention to provide an X-ray exposure time recording apparatus adapted for medical use which will provide an individual record of the total exposure time of each individual patient.

It is a further object of this invention to provide an X-ray exposure time recording apparatusadapted for medical use which will provide an .1 individual record of the total exposure time of each individual patient and which will also provide a record of the exposure time of each individual incremental exposure comprising a part of said total exposure time.

, as it appears after receiving markings from a recording stylus.

Generally speaking, one embodiment of my invention comprises a cabinet or other suitable housing provided with a suitable hinged door which opens upwardly to permit access to a record chart within the housing. Within the housing there is a recording carriage, such as a disc, adapted to receive and carry a record chart,

the carriage being driven by a synchronous or other constant speed motor. Selectively operable means are provided for holding a markable chart upon the carriage, and such means may cooperate with a switch to interrupt, a primary circuit (connected to or controlling a source of radiation) when attempt is made to remove the chart.

A frame or carriage carrying a pencil, pen, scribe, stylus, voltage-carrying stylus, or the like, is mounted for movement with the recording carriage. Means are provided for arresting and immobilizing the stylus carriage and thereby attaining relative, recording motion between stylus and chart when the source of radiation is being used.

The device also includes a timing motor. and suitable circuit operable by a cam driven thereby, the circuits warning the operator when a predetermined total time of radiation has transpired, even though such total time is the summation of a number of shorter time increments. Means are also provided for energizing the timing motor only when the stylus is recording, and for returning the timing cam to original position when, prior to the expiration of the predetermined total permissive time of radiation, the operator desires to remove the chart.

More specifically, the embodiment illustrated shows the upper surface of cabinet 5 provided with a door 2 hinged at 3. The center portion of the door 2 is provided with a transparent window A supporting member 5 is mounted in any suitable manner upon the base 6 of the cabinet.

A hollow shaft 8 is rotatably mounted or journaled in the upwardly extending portion 9 of the supporting member 5. A circular, discshaped member [0 (record chart carriage) is fixedly mounted on the upper end of the hollow shaft 8 so as to be driven thereby. The member It is provided with upwardly extending locating pins H and H2. The exterior surface of the upper end of the rotatable shaft is threaded at E3. A manually operable chart-holding or clamping means. M is interiorly threaded at [5, said threads cooperating with the exterior threads 13 on the upper end of the hollow shaft 8. A longitudinal, switch-actuating member 7 is mounted within and coaxial with the hollow shaft 8. The upper end of said switch-actuating member I abuts the interior surface of the clamping means Hi. The lower end of said switchactuating member i abuts and actuates an electrical switch 42, normally holding this switch in open position.

A synchronous or constant speed motor I6 is also mounted on the supporting member 5 for rotating the hollow shaft 8, disc member it], and clamping means i l through reduction gearing indicated generally at H when said motor i6 is energized. The lower surface of an annular ring the circular disc member iii.

I8 frictionally engages the upper surface of an annular lip portion i9 of the member It] so as'to be driven thereby. Spring members 20 may be fixed to the annular ring E8 so as to be in opposition to the annular member ii] on the opposite side of lip i9 from the annular member M3 for maintaining frictional engagement between said annular member i8 and the annular lip Iii of An annular ring 2| is fixed to the annular member [8.

A supporting member 22 is fixed to the supporting member 5 and supports an electromagnet 23 in a vertical position. A supporting member 24 is fixed to the supporting member 22. Said supporting member 2 3 extends in a vertical direction parallel to the electromagnet 23 and the electromagnet 23 rests against the innerlower face 'of said supporting member 24, as viewed in Fig; 2, in opposition'to and spaced from the pole face 26 f the electromagnet 23. Said armature 25 'i'siconnected to a retaining pin 21 which passes through the supporting member 24. The outer end of the retaining pin 27 has a retaining member or collar 28 thereon. A coil compression sping 29 is mounted between the retaining member 28 and the supporting member 24 so as to spring bias the armature 25 in an upward direction and maintain said armature 25 at a spaced distance away from the pole face 26 of the electromagnet 23- until' said electromagnet 23 is energized. When said electromagnet 25 is energized, the-armature 25, retaining pin 2'. and retaining collar 28 move in a downward direction against the force exerted by the spring 29 and-abut the annular rin 25, thus fixedly looking said annular rings and H! from rotation.

A stylus holder or carriage 35 is mounted on the upper surface of annular ring l8, said stylus holder 30 carrying asuitable stylus, recording pen, or scribe, etc. of any of the types well known inthe art. The stylus holder 30 is of the type which allows movement of the stylus 3i so that the' stylus 3| and stylus holder 38 may be manuallypicked up and removed-from the recordable medium so that said recordable medium may be removed from the circular disc member I!) when so'desired. Said stylus holder 35 has mounted thereon a stylus-actuating solenoid 6'], for actuating or moving said stylus and stylus holder radially with respect to the circular disc member l0; A brush 32 contacts a circular, electrically conductive member 33 which is connected to a suitable source of electrical power through power supply switch 45 and annular member 2| contacts brush member as which is connected to switch 46, power supply switch 48 and the electrical power source. The stylus-actuating solenoid 61 which is contained within the stylus holder 86 is electrically connected to the brush 32 and the annular ring 2i for actuating the same upon energization.

Switches 35 and 35 are mounted on the wall ofthe cabinet I so that when the door 2 is opened said switch s will also be opened and when the door 2 is closed said switches will be closed.

Warning lights Bl and 38'are so mounted within the cabinet with relation to an opening 39 in the cabinet that they may be observed from the outside of the cabinet i. A power supply switch fl ismounted in the wall of the cabinet i adjacent the orifice 39' with the switch portion projecting through the wall of the cabinet so that said switch as may be actuated from outside of the cabinet.

A'- control box 4! is mounted on the base of the cabinet. Said control box fill contains a relay or solenoid coil 43 and normally open switches 44, 45,- and 26 which are closed by said relay coil 43 whenenergized. Said control box 4| also contains arelay or solenoid coil l! which closes normally open switches 48, 49, and B and opens normally closed switch 5! simultaneously. The control box 4] also contains relay or solenoid coil 52 which closes normally open switch not shown for closing the electrical circuit to an X-ray generator, not shown. The control box il also contains a synchronous or other constant speed time control motor 54 and cam 55 which opens normally closed switches 58 and 51 and which closes normallyopen switch 58 simultaneously. The time control motor-54drives a shaft59-which has keyed thereon the cam 55 by means of a. key 60] The: cam 551s slidably mounted on the shaft'59. The: cam 55is provided with projections 51 which will abut and actuate switch-actuating members fi'i and 63 twice during each complete revolution of cam 55. The switch-actuating member 62, when abutted by the projections 51 on cam 55', closes switch 58 and opens switch 5?. The switch actuating member 63, when abutted by the projections 6| on the cam 55, opens switch 56'. All

of the abovementioned switch opening or closing actions take place simultaneously.

A manually operable, hollow; tubular, camoverriding member 54 which is provided with a closed outer end is mounted in a hole in the wall of the cabinet i and is retained therein by a cir-- cumferential lip 68. Said member 54 is loosely fitted over the outer end of the shaft 59' of the time control motor 55 and abuts the upper surface of the cam 55 as viewed in Fig. 3."

place to cause the projections 6! to clear the switch-actuating members 62 and 63, at which time a spring 65 will return the cam 55 to its normal position.

Wheneverthe power supply switch 49 is closed and the door 2 is closed, thus closing the dooractuated switch 36, which closes the circuit to the constant speed disc-driving motor 15, the motor !5 rotates the circular disc member iii, the recordable medium carried by said disc member It, and the frictionally engaged, annular ring 18 and attached annular ring 2|. motion takes place between the stylus 3| carried by stylus holder 30 which is mounted on the annular ring [8 and the recordable medium carried by the circular disc member ill. However, whenever the electromagnet 23 is energized, the armature 25 frictionally engages the annular ring member 2! overriding the frictional engagement between the circular disc member l5 and the annularring l8 and thus prevents any rotation of the annular ring member 2|, the annular ring member [8, and the stylus holder 35 which is mounted therein. Since, under this condition, the circular disc member I 5 continues to rotate while the annular rings 21 and i8 and attached stylus holder 35am locked in a stationary position, relative movement takes place between the stylus 3i and the recordable medium carried by the circular disc member iii during the period of energization of said electromagnet 23.

The normal operation of the device is as follows: The physician or operator of the apparatus closes power supply switch =35, depresses the camoverriding member cc and closes a normally open foot switch 65. If the door-actuated switch 35 is closed, which condition will exist if the door 2 is closed, and if switch 5! is closed, which it normally is, and if the contact 5? is closed, which it normally is, the relay or solenoid coil 52 and the relay or solenoid coil as will be energized simultaneously. Said relay or solenoid coil 52 will lay or solenoid coil-53' will simultaneously close" Said: tubular member 84 may be manually depressed so as to slide the cam 55 downwardly on the shaft Thus no relative normally open switches M, as, and 45. The

closing of the switch 45 will energize the elec-.

tromagnet 23 which will lock the annular rings 2| and I8 and the stylus holder 30 and stylus 3| mounted thereon from rotation, and since the door-actuated switch 36 is closed by the door 2 thus causing constant speed, disc driving motor I to rotate the circular disc member Hi and the recordable medium mounted thereon with respect to the stationary stylus 3|, said recordable medium is recorded by means of said stylus 3| for the period of energization of the X-ray generator. The closing of the switch 55 will close the circuit to the time control motor 55, starting rotation of the same. The closing or switch 45 will close the circuit to the stylus-actuating solenoid El contained in the stylus holder 30 and, will radially, outwardly actuate and hold said stylus holder 35 and said stylus 3| during the period of energization of the X-ray generator. If the foot switch 65 is released, all of the above actions cease. The foot switch 65 may be or" the type which, when depressed and closed, locks itself until further actuation for releasing it takes place, if so desired.

After the foot switch 65 is closed and the above-described action takes place, time control motor 54 rotates the cam 55 until such time as the projections 6| actuate switch-actuating members 62 and 53, thus automatically Shutting off the X-ray generator at the end of a 180 rotation of the cam 55. At such time after the cam 55 has rotated 180 and has actuated members 62 and 63 and stopped the action of the X-ray generator, the tubular member 5 4 may be manually depressed, thus moving the cam 55 and projections 6| below the plane of the switch-actuating members 52 and 63, thus allowing the switches 56 and 5i to close and switch 58 to open and the X-ray generator will again start and the whole above-described operation will be repeated.

The switch 58, which is closed whenever the switches 5! and 56 are open, closes the electrical circuit to a red warning light 58 so that whenever the cam 55 has gone through a 180 rotation and the projections 6| open the switches 55 and 51 and close the switch 58, the red warning light gones on, warning the operator that the operation has terminated and that resetting of the cam 55 by means of the tubular member 64 is necessary if further operation of the device is desired.

Following the above operations through step by step: after the foot switch 55 is closed and the before-described action takes place, the time control motor 54 rotates the cam 55 through 185 or until such time as the projections 6| on said cam 55 actuate switch-actuating members 62 and 63 which will simultaneously open normally closed switches 55 and 5'5 and close normally open switch 58. The opening of said switch 5i breaks the oilcuit tothe relay or solenoid coils 33 and 52. The deenergizing of the relay or solenoid coil 52 allows normally an open, X-ray power supply switch, not shown, to open, thus causing the X ray generator to cease operation. The deenergizing of the relay or solenoid coil 43 allows normally open switches 45, 55, and 56 to open. The opening of said switch M breaks the circuit to the electromagnet 23, thus releasing annular rings 2| and i8 and stylus holder 30 mounted thereon which causes the recording by the stylus 3| of the recordable medium carried on the rotating, circular disc member ID to cease. The opening of said switch 45 breaks the circuit to the cam-driving, timing motor 54, causing it tostop with the cam 55 positioned as shown in Fig? 4, which I call home position. The opening of the switch 46 breaks the circuit to stylus-actuating solenoid 6'1, allowing spring means, not shown, to move the stylus holder 3|] and stylus 3| in a radial, inward direction with respect to the circular disc member l5 and the recordable medium carried thereon, thus marking the beginning and the end of each individual recording period on said recordable medium.

The above-mentioned cam-actuated closing of the normally open switch 58, when the cam 55 reaches home position, closes the circuit to a red warning light 38 which warns the physician or operator of the X-ray apparatus that the predetermined total exposure time interval has passed and that the cam 55 has reached home position, as shown in Fig. l. The above-men tioned cam-actuated opening of the normally. closed switch 56, when the cam 55 reaches home position, has no effect under the above conditions.

The above description is true if the total elapsed exposure time comprises one continuousexposure or a plurality of small, incremental exposures, provided that the examination is not concluded and the recorded medium is not removed before the cam 55 reaches home position.

If the foot switch 66 is released before. the cam 55 has gone through a rotation, or before the cam 55 has reached home position, and the projections 5| have actuated the switchactuating members 62 and 63, the switch 56 will be closed, and if at such time the clamping means M which threadably engages the upper end of the rotatable shaft 8 for clamping a recordable medium on the circular disc member I5 is removed, the switch 42 is also closed, thus closing the electrical circuit to a relay or solenoid coil 4': which, in turn, will open the normally closed switch 5| which deenergizes the solenoid or relay coil 52, thus allowing the normally open, X-ray power supply switch to open, thus interrupting the operation of the X-ray generator. The relay or solenoid coil 47, simultaneously with the opening of the switch 5|, will close the switch 55, which will close the circuit to time control motor 55, thus causing said time control motor to rotate until the projections 6| contact and actuate the switch-actuating members 62 and 63 which will open the switch 56, thus breaking the circuit to the relay or solenoid coil 41. Simultaneously to the opening of the switch 5| and the closing of the switch 55, switches 49 and 48 are also closed. The switch 49 acts as a shunt around the switch 52 so that even when the clamping means hi is screwed down on the upper end of the hollow shaft 8, thus causing the switch-actuating member to open the switch again, current will still be supplied to relay or solenoid coil 5'5 as long as switch 56 is open, or, in other words, until the time control motor has rotated the cam 55 and projection 6| to the p0-. sition shown in Fig. l, which we will call home position. The switch 48, which closes at the same time the switch 5| opens and switches 50 and 55 close, closes the electrical circuit to yellow warning light 37, which warns the operator of the device that the cam 55 is not in home position, as shown in Fig. 4. As soon as said cam 55 has reached home position, as shown in Fig. l, the yellow warning light will go out,

since the opening of the switch 56 will have broken the circuit to the relay coil 41.

Following the above operations through step by v predetermined time interval has passed or before the cam 55 reaches home position, the abovereferred to, normally closed, cam-actuated switch 56 is closed and when the retaining, clamping member I4 is also unscrewed from the upper end of the hollow shaft 8 for removing the recorded medium from the upper surface of the circular disc member Hi, the normally closed switch 42 is allowed to close, thus closing a circuit through said switches 56 and 42 to a relay or solenoid coil 41. The energization of said relay or solenoid coil 41 simultaneously closes normally open switches 48, 49, and 50 and opens normally closed switch 51. The closing of said normally open, holding switch 49 shunts or by-passes the switch 42 and acts to keep the circuit to said relay or solenoid coil 41 closed entirely independently of the switch 42 provided that the cam-actuated switch 56 is closed. In other words, it is necessary to have both the cam 55 in a position other than home position, thus allowing switch 56 to x close, and to remove the retaining, clamping member I4, thus also closing switch 42 in order to initially energize the relay or solenoid coil 41. But once said relay or solenoid coil 41 is energized, the clamping means l4 may or may not be replaced, or switch 42 may or may not be opened 7 or closed without having the slightest effect on relay or solenoid coil 41. Said relay 41 will be deenergized when the cam 55 reaches home position and the projections 6| on said cam 55 actuate switch-actuating means 63, thus opening cam-actuated switch 56 and breaking the circuit to said relay or solenoid coil 41. v

The before-mentioned closing of said normally open switch 48 by relay or solenoid coil 41 closes the circuit to the yellow warning light 31 and warns the physician or operator of the apparatus that the rotating cam 55 has not yet reached home position. The before-mentioned closing of the normally open switch 50 by the relay or solenoid coil 41 closes the circuit to the cam-driving timing motor 54 for returning the cam 55 to home position. The before-mentioned opening of normally closed switch by said relay or solenoid coil 4'5 opens the circuit to relay or sole- .noid coils 43 and 52. The deenergizing of the .relay or solenoid coil 43 allows normally open switches 44, 45, and 46 to open. The opening of switch 44 breaks the circuit to electromagnet 23', thus stopping the recording by the stylus 3| of the recordable medium ,as hereinbefore explained. The opening of the switch 45 has no effect, since said switch 45 is shunted by. Switch 50 which is closed under this condition.v The opening of switch 45 breaks the circuit to the stylus-actuating solenoid 61, thus allowing spring means, not shown, to radially, inwardly move said stylus 3! a short distance with respect to circular disc member ill. The before-mentioned opening of the circuit to said relay or solenoid coil 52 deenergizes the same and allows the normally open X-ray power supply switch to open, thus causing the X-ray generator to cease operating.

The opening or closing of the door 2 actuates switches 35 and 36, the opening of the door opening the switches and the closing of the door closing the switches. The opening of the door 2, thus opening the switch 35, will stop the X-ray generator regardless of all other switches or mechanism, and the closing of the door 2 will place lyO iii

the device in condition for operation again. The opening of the door 2 opens the switch 36 which closes the circuit to the synchronous or constant speed motor H5 which rotates the circular disc member 18, and when the door 2 is opened, the motor l6 stops, thus making it possible to unscrew the clamping means 54 from the end of the hollow shaft 8 and remove the recordable medium from the upper surface of the circular disc member I'U.

It is to be clearly and distinctly understood that the stylus-actuating solenoid 61, which is contained in the stylus holder 38, may be eliminated and not affect the function of the device. The circuit can readily be rearranged so as to eliminate the yellow warning light 3i and red warning light 38 and associated switches 48 and 58 without affecting the function of the device.

The apparatus in modified form may be used in electrical overload or surge recording or for recording the length of time of departure of any physical condition from a predetermined norm. This can be accomplished by eliminating all elements of the apparatus other than the synchronous, disc-driving motor, reduction gearing, shaft, circular disc member adapted to carry a recording medium, stylus and stylus holder, the annular member which is in engagement with the outer edge of the circular member, the armature which looks the annular member against rotation and electromagnetic means for actuating the armature so as to lock the annular member against rotation while allowing rotation of the circular disc member. Suitable switch means will be provided, of course.

The electromagnetic means mentioned might be an overload relay which acts only on electrical surges or overloads, thus allowing relative movement between the stylus and recordable medium only during the period of time of such surges or overloads. Or such electromagnetic mean might be differential relays which are actuated by an electrical current which departs in either direction from the norm, said electrical current being responsive to the .physical condition which it is desired to keep track of.

Numerous other modifications of this principle will suggest themselves to those skilled in the art. The example given is for illustrative purposes only and I do not desire to limit myself to the example shown. My invention is to be limited only by the scope of the claims appended hereto.

I claim:

1. A radiationtirne recording and control apparatus comprising: a normally rotatable annular member; recording stylus means mounted on said annular member; rotatable disc means adapted to carry a removable record-receiving medium for recording cooperation with said recording stylus means, a portion of said disc means being in spring-pressed, frictional, rotative driving engagement with said annular member; constant speed motor means for rotating said disc means and said annular member; looking means for locking said annular member against rotation during the period of radiation, thereby relatively to move said stylus and a record-receiving medium carried by said disc; timing motor means; and cam means driven by said timin motor means adapted to shut off the source of radiation after a time interval.

2. A radiation time recording and control apparatus comprising: a normally rotatable annupredeterrnined lar member; recording stylus means mounted on said annular member; rotatable disc means adapted to carry a removable record-receiving medium for cooperation with said recording stylus means, a portion of said disc'means being in spring-pressed, frictional rotatable driving engagement with said annular member; constant speed motor means for rotating said disc means and said annular member; locking means for locking said annular member against rotation during the period of radiation, thereby to move said'disc and a movable record-receiving medium carried thereby relatively to said stylus; and timing means adapted to shut off the source of radiation and unlock said lockin means after a predetermined time interval.

constant speed motor means for rotating said.

disc means; and lockin means for locking said annular member against rotation during the recording period.

4. In an apparatus for recording the extent of use and limiting the use of a source of radiation, including a motor-driven recording carriage and means for holding a record chart on said carriage: a timing motor provided with a cam;

a separate circuit including an electrically operated switch for energizin a source of radia- -'tion; a stylus carriage normally movable with the recording chart carriage; a primary circuit including a switch operable by the cam, said switch being open when the cam is in home position, operably connected to the electrically operated switch; means rendered operable by closure of the cam-operated switch to arrest the stylus and to energize the timing motor; and manual switch means in the primary circuit for a controlling the operation of the electrically controlled switch while the cam-operated switch is closed.

5. In an apparatus for recording the extent of use and limiting the use of a source of radiation, including a motor-driven recording carriage and means for holding a record chart on said carriage: a timing motor provided with a cam; a separate circuit including an electrically operated switch for energizing a source of radiation; a stylus carriage normally movable with the recording chart carriage; a primary circuit including a switch operable by the cam, said switch being open when the cam is in home position, operably connected to the electrically operated switch; manual means for closing the cam-operated switch; means rendered operable by closure of the cam-operated switch to arrest the stylus and to energize the timing motor; and manual switch means in the primary circuit for controlling the operation of the electrically controlled switch while the cam-operated switch is closed.

6. In an apparatus for recording the extent of use and limiting the use of a source of radiation, including a motor-driven recording carriage and means for holding a, record chart on said carriage: a timing motor provided with a cam; a separate circuit including an electrically operated switch for energizin a source of radiation; a stylus carriage normally movable with the recording chart carriage; a primary circuit including a switch operable by the cam, said switch being open when the cam is in home position, operably connected to the electrically operated switch; manual means for closing the cam-operated switch; means rendered operable by closure of the cam-operated switch to arrest the stylus and to energize the timing motor; manual switch means in the primary circuit for controlling the operation of the electrically controlled switch while the cam-operated switch is closed; and means for interrupting the primary circuit when the chart holding means is released.

' '7. In an apparatus for recording the extent of use and limiting the use of a source of radiation, including a motor-driven recording carriage and means for holding a record chart on said carriage: a timing motor provided with a cam; a separate circuit including an electrically operated switch for energizing a source of radiation; a stylus carriage normally movable with the recording chart carriage; a primary circuit including a switch operable by the cam, said switch being open when the cam is in home position, operably connected to the electrically operated switch; manual means for closing the cam-operated switchj means rendered operable by closure of the cam-operated switch to arrest the stylus and to energize the timing motor; manual switch means in the primary circuit for controlling the operation of the electrically cohtrolled switch while the cam-operated switch is closed; and means fOr supplying energy to the timing motor to return the cam to home position when the chart holding means is released.

8. In an apparatus for recording the extent of "use and limiting the use of a source of radiation,

including a motor-driven recording carriage and means for holding a record chart on said carriage: a timing motor provided with a cam; a separate circuit including an electrically operated switch for energizing a source of radiation; a stylus carriage normally movable with the recording chart carriage; a primary circuit including a switch operable by the cam, said switch being open when the cam is in home po sition, operabl connected to the electrically 010- s erated switch; means rendered operable by closure of the cam-operated switch to arrest the stylus and to energize th timing motor; manual switch means in the primary circuit for controlling the operation of the electrically controlled switch while the cam-operated switchlis closed; and means for supplying energy tothe timing motor to return the cam to home'position when the chart holding means is released.

9. In an apparatus for recording the extent of use and limiting the use of a source of radiation, including a motor-driven recording carriage and means for holding be, record chart on said carriage: a timing motor provided with a cam; a separate circuit including an electrically operated switch for energizing a source of radiation; a stylus carriage normally movable with the recording chart carriage; a primary circuit including a switch operable by the cam, said switch being open when the cam is in home position, operably connected to the electricall operated switch; manual means for closing the cam-operated switch; means rendered operable by closure of the cam-operated switch to arrest the stylus and to energize the timing motor; manual switch means in the primary circuit for controlling the operation of the electrically controlled switch while the cam-operated switch 13 is closed; means for interrupting the primary circuit when the chart holding means is released; and means for supplying energy to the timing motor to return the cam to home position when the chart holding means is released.

10. A radiation time recording and control apparatus comprising: a pair of concentrically related rotatable members, one of said members being arranged to carry a record-receiving medium and the other carrying a recording stylus; a constant speed motor operably connected to drive one of said members; means normally holding said pair of members in engagement for simultaneous, non-recording rotation; and locking means for immobilizing one of said members during a period of radiation while the other member is rotated, to record duration of such period by the stylus upon a record-receiving medium.

11. A radiation time recording and control apparatus comprising: a pair of concentrically related rotatable members, one of said members being arranged to carry a record-receiving medium and the other carrying a recording stylus; a constant speed motor operably connected to drive one of said members; means normally holding said pair of members in engagement for simultaneous, non-recording rotation; locking means for immobilizing one of said members during a period of radiation while the other member is rotated, to record duration of such period by the stylus upon a record-receiving medium; a timing motor; and a circuit including means arranged to close a power circuit to a source of radiation to energize the timing motor and to energize said locking means simultaneously, said timing motor being operably associated with switch means for breaking said circuit upon expiration of a predetermined time.

12. A radiation time recording and control ap paratus comprising: a, rotatable stylus carriage including means for carrying a recording stylus; a rotatable member arranged for rotation concentrically with said stylus carriage, said rotatable member being arranged to carry a record-receiving medium in cooperative relation to the stylus on said carriage; means normally maintaining said stylus carriage and rotatable member is engagement for simultaneous, nonrecording rotation; constant speed motor means for driving said rotatable member; electromagnetic locking means for immobilizing the stylus carriage during the period of radiation to produce relative recording rotation between the stylus carriage and rotatable member; timing motor means; and cam means driven by the timing motor means and arranged to shut off the source of radiation after a predetermined time interval.

WILLIAM B. POND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,877,260 Wantz Sept. 13, 1932 2,991,697 Wolf Aug. 31, 1937 2,126,957 Goldfield Aug. 16, 1938 2,351,486 Constable et a1. June 13, 1944 2,353,980 Weisglass July 18, 1944 FOREIGN PATENTS Number Country Date 586,532 7 Germany Apr. 20, 1929 

